Dermatologists list 5 lesser-known skin saboteurs

You know about sun and smoking-induced damage. Here are the other, more surprising things that flick off your skin's light switch.

1.The thermostat: "Heat and air-conditioning are two of the most common causes of dry, dull skin," says Jeannette Graf, assistant clinical professor of dermatology at Mount Sinai School of Medicine in New York City. A humidifier is a simple, effective solution.

2.Lack of sleep: "Your skin can rebound from the occasional late night, but if you usually get less than six or seven hours, it'll catch up with you," says Amy Wechsler, a New York City-based dermatologist.

4. Eating like a teenager: "Sugary foods break down collagen and elastin, causing dullness and wrinkles over time," says Fredric Brandt, a dermatologist in New York City and Miami. "Alcohol is dehydrating and causes inflammation, which makes your skin red and dry."